In Situ Probing and Phosphate-Assisted Recovery of Proton Transfer to Eliminate H2O2 Formation in the Oxygen Reduction Reaction.

IF 14.4 1区 化学 Q1 CHEMISTRY, MULTIDISCIPLINARY
Xiang Li, Chuanqi Cheng, Qingqing Ruan, Ying Gao, Lingjun Kong, Yanmei Shi, Bin Zhang
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Abstract

Single-atom Fe-N-C is a promising candidate for the oxygen reduction reaction (ORR) at the cathode of proton-exchange membrane fuel cells (PEMFCs). However, under strongly acidic conditions, Fe-N-C suffers from severe oxidation from Fenton reactions caused by trace amounts of dissolved Fe and a 2-electron (2e) ORR product of H2O2. Herein, we demonstrate a facile and general strategy to nearly eliminate the 2e path of the ORR by introducing phosphates. We discover that bubbling O2 into water introduces an inherent problem in breaking the hydrogen-bond network and thus hindering proton transfer, resulting in a decreased 4e ORR selectivity. Introducing phosphates is found to recover the hydrogen-bond network to eliminate the 2e path. This strategy works well for Fe-N-C, commercial Pt/C, and even carbon catalysts with a dominant 2e selectivity, resulting in negligible H2O2 production and better stability in both the rotating ring-disk electrode system and flow cell. Our work provides deep insight into the ORR mechanism and a useful strategy to lower the cost and lengthen the lifetime of PEMFCs by using nonnoble metal electrocatalysts as cathodes.

原位探测和磷酸盐辅助恢复质子转移以消除氧还原反应中H2O2的形成。
单原子Fe-N-C是质子交换膜燃料电池(pemfc)阴极氧还原反应(ORR)的理想材料。然而,在强酸性条件下,Fe- n - c由于溶解的微量Fe和H2O2的2电子(2e) ORR产物引起的Fenton反应而遭受严重氧化。在这里,我们展示了一种简单而通用的策略,通过引入磷酸盐几乎消除了ORR的2e路径。我们发现,将O2泡入水中会带来一个固有的问题,即破坏氢键网络,从而阻碍质子转移,导致4e ORR选择性降低。发现引入磷酸盐可以恢复氢键网络,从而消除2e路径。该策略适用于Fe-N-C、商用Pt/C,甚至具有主导2e选择性的碳催化剂,在旋转环盘电极系统和流动电池中产生H2O2几乎可以忽略不计,并且具有更好的稳定性。我们的工作提供了对ORR机制的深入了解,并通过使用非贵金属电催化剂作为阴极,为降低成本和延长pemfc的使用寿命提供了有用的策略。
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来源期刊
CiteScore
24.40
自引率
6.00%
发文量
2398
审稿时长
1.6 months
期刊介绍: The flagship journal of the American Chemical Society, known as the Journal of the American Chemical Society (JACS), has been a prestigious publication since its establishment in 1879. It holds a preeminent position in the field of chemistry and related interdisciplinary sciences. JACS is committed to disseminating cutting-edge research papers, covering a wide range of topics, and encompasses approximately 19,000 pages of Articles, Communications, and Perspectives annually. With a weekly publication frequency, JACS plays a vital role in advancing the field of chemistry by providing essential research.
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